Steam power plants comprise one or more steam turbines, also referred to as “units”. Each unit comprises a high-pressure turbine, an intermediate-pressure turbine and a low-pressure turbine. The expanded steam is conducted by a steam exhaust from the low-pressure turbine to a condenser. The condenser is connected to a cooling system, for example a wet cooling tower. Wet cooling towers have a great cooling performance, but require cooling water.
In case that the power plant comprises more than one turbine in most cases the exhaust of all turbines is connected to one main condensing system. This layout is appropriate if sufficient cooling water for condensing the steam is available.
Today there is a growing need to adapt the operating regime of existing power plants to changing boundary conditions, resulting from e.g. climate change or environmental restrictions. Especially seasonal restricted water supply and a shortage in cooling water make-up resulting thereof, has led for power plants to forced load reductions.
Consequently, it is an object of the claimed invention to provide a steam power plant with a reduced dependency of the electrical output from the available cooling water resources.
In other words: the steam power plant according to the invention should be able to maintain a high electricity output, even if the cooling capacity of the regular condenser is reduced due to temporary shortage of cooling water.
A further object of the invention is to reduce the cooling water consumption of the power plant.
These objectives are achieved by means of a steam power plant with at least one steam turbine comprising a low-pressure turbine and a main condensing system, by adding a second low-pressure turbine and a second condensing system, which is preferably an air cooled condenser (ACC).